The Chinese Straddle Bus Exists! What Now?

As I said before, I think that especially in wealthy countries, this thing is mostly useful as a parable, whose message is: Look how much money people will spend on infrastructure whose sole purpose is to avoid taking any space from motorists.

If the thing has any application, it’s probably not in Europe or North America, because:

It’s massively capital intensive. The little rail-like running-ways in the street are the least of it, and the fleet is the second-least. The stations must be massive elevated structures, with a mezzanine above the top of the bus. Existing bridges would almost all need to be raised. Countries with high construction costs will find this a barrier.

It will serve stations located on expressways, which tend to be bad places for the pedestrians that the bus will attract and disgorge. The only solution to this is massive grade separation, leading to a continuous pedestrian plane at the station level, well above the street. This leads to urban design that essentially abandons the ground plane to cars and rebuilds an entire pedestrian city above it.

The vast raised pedestrian plane was a hot idea for about 15 minutes in the 1970s, giving us London’s Barbican, Paris’s La Défense, Los Angeles’s Bunker Hill, etc etc. Today, most European and North American urbanists hate these places and insist on solving problems on the ground plane, though of course the pendulum could swing again. But it’s much more common and accepted in East Asia, and to some extent in former Soviet countries.

There’s also the problem that if you build this thing in an existing dense city, you are building it right outside of someone’s window. So you probably need a political structure that can make and enforce highly controversial decisions, as opposed to the kind of deference to public protest that prevails in most Western democracies.

You really have to redesign big districts around this thing, which is another big barrier unless we are talking about entirely new areas. A high pedestrian plane only works if the idea is shared by many surrounding buildings.

Where this thing connects with underground subway lines, your mezzanine for this elevated thing is at least four stories away from the subway’s mezzanine. This requires high-volume vertical circulation, which no inventor has ever really cracked. Elevators are really inefficient at high volume, and escalators are really slow at it.

The nature of this technology makes it hard to demonstrate at the right scale. There is a basic conflict between “huge capital expenditure” and “demonstration of new technology.” It’s the same problem that monorails and maglevs and “Personal Rapid Transit” and many other cool ideas have had. Inventors need places to do demo projects. But it’s not smart for a city to agree to be Version 1.0 of something, while also spending billions on the assumption of its permanent success. This is how cities end up with stranded transit assets that can become net barriers to good transit (see Scarborough RT, Toronto, or the airport maglev in Shanghai, etc etc.)

(Update: In the third top-level comment below, Brian Smith points out that the surface space this thing takes is still wider than a bus lane, so why not just do aa busway? He also points out that the vehicle is rigid and the test track was straight. What happens when it goes around curves? It takes more horizontal space of course. And it seems to rely on a ground-level third-rail, which is considered wildly unsafe in the business.)

Having said that, if anyone can pull this off at scale, it’s probably China, which seems to tick all the boxes I’ve identified. They have the sufficiently centralized decision making, low enough construction costs, ability to do things at scale, and relative indifference to Western aesthetics that this thing requires. They are also building entirely new districts, which offer the best possibility for actually organizing a place around the correct elevated ground plane. So yes, it may happen, and it may do some good. Which doesn’t mean it’s not, deep down, ridiculous.

29 Responses to The Chinese Straddle Bus Exists! What Now?

I am happy that this bus got built. Although there will be many (justified) criticisms of it, I am happy because experimentation and the evolution that comes from it gives us new things that can be so useful to us all. Trams and buses evolved from horse-drawn carts in the late 1800s if I am correct.

This is part of that magic experimentation that is innovation. Most experiments will fail. Some will not. Others will be refined. I welcome it.

Firstly, this vehicle has a very spacious interior and high capacity. Current train and bus vehicles do not have this. Somewhere like China and other high population countries need something that is high capacity, but tend to be stuck to standard gauge trains. The innovation here is that the “gauge” is much broader and thus much higher capacity.

Secondly, many places have freeways. This could work in places like that as a retrofitting thing, though I do take your point about low bridges.

Thirdly, freeways as being bad transit places. With the right surrounding network of smaller feeder buses, I cannot see why the bus would fail. Perth, Australia, for example, runs trains in the middle of freeways. The stations are there also. Yet the patronage for the lines set up this way is easily 50 000 – 60 000 passenger trips per day. How? Feeder buses to stations in the freeway median.

Fourthly, lifts and elevators not being high volume. Plenty of metros are built underground and the way people exit that is through multiple lifts and elevators. Why can’t that be applied here?

Good luck to the inventors for having a go and risking time, money and effort. Best of luck to them!

I suppose compared to regular elevated rail it would leave the airspace clearer (when the vehicle isn’t there). I still find it hard to believe it can be more cost-effective than an automated elevated rail or monorail system, but I guess the Chinese are now the people to have the gumption to try these things out and find out for sure.

I was in China a fortnight ago working on transit interchanges and this thing came up again. I agree that it is pointless, complex and contrived ‘solution’ to a problem (surface traffic congestion) that has a straightforward but politically difficult solution (deter private vehicle use).

The funny thing is the more effective transit priority solution is right there, partially hidden in the straddle bus proposal. Look at the width of it. It effectively occupies more than 2 traffic lanes, so while it potentially straddles two lanes (though only if trucks or cars with roof loads aren’t using those lanes), the tracks and other structure eat into another lane.

So if a city is prepared to give up the road space to fit this thing in, they could just dedicate that space to conventional bus rapid transit at a much lower cost.

There are a couple of technical barriers that I’m sure the proponents know about but which I don’t think they can solve without compromising the concept beyond feasibility. The video animation at Shangaiist (http://shanghaiist.com/2016/08/02/straddling_bus_launch.php) shows the rigid parts of the vehicle bending so it goes around a corner; and the scale model test had huge articulations that would compromise the internal space. The test track is straight and the test vehicle is rigid, so the full-scale test isn’t going to highlight this shortcoming. I don’t think this thing can go around corners more effectively than heavy rail. I can’t see how it could be fitted into any existing roads in China. I doubt it could climb a grade greater than two or three percent.

The weight and the massive change to urban form required to provide stations for it are two other big barriers in my view. The concept has been around for 10 years and I’m surprised it hasn’t died a deserved death before now.

Excellent points. Even better than a bus lane would be an elevated rail option. Supports could easily fit into that same space, and you would gain:

– full grade separation. That means increased reliability, speed, and capacity, all without messing with car traffic and signal timing below (where you can put buses)
– the ability to go around corners. That in turn allows longer vehicles, negating capacity advantages of the wide vehicle.
– More width available for stations. That eases problems with vertical circulation, being next to people’s windows, and elevated pedestrian space.
– off the shelf parts. Cheaper, more reliable, easier to get ahold of.

I applaud the creativity, but this is a classic case of trying to build a better mouse trap.

Better mouse trap or not, we’ll be stuck debating the concept for quite a while, and I’m afraid the case boils down to sheer aesthetics and emotional arguments rather than these more rational ones.

Case in point, Mr. Aravena, a Pritzker prize architect (who received the top award architects reward to a living fellow) recently proposed the straddle bus to replace the Charlotte streetcar’s eastern leg on Central Avenue, a predominantly wide 5-lane boulevard corridor without overpasses. Here, it’s straddle bus vs. the streetcar, running in mixed traffic, which (if it ever gets funded) is also taking down all the overhead masts.

Thankfully, there’s a fatal flaw for the straddle bus, and it will not be height challenges in this case – in fact it may provide a surface solution where the CSX line crosses the corridor – it will be the width in the 4-lane section through the Plaza Midwood commercial district.

“Where this thing connects with underground subway lines, your mezzanine for this elevated thing is at least four stories away from the subway’s mezzanine. This requires high-volume vertical circulation, which no inventor has ever really cracked. Elevators are really inefficient at high volume, and escalators are really slow at it.”

And that is one of the reasons why the Scarborough RT is so hated by those who use it…the slow 4 storey trip between subway platform level and the RT Platforms

Now, it only took about 3 minutes, but it was the principle of the thing that probably upset people the most.

One point that hasn’t got a lot of attention is that the clearance under the vehicle (as shown in the video) is only 2.1 metres. That will fit a standard sedan or SUV, but any kind of truck, minivan, ambulance or even cyclist is unlikely to fit underneath.

Here in Melbourne we have enough trouble keeping motorists of high vehicles away from low bridges (down to about 3 metres or so). The prospect of such hazards moving around the road system doesn’t bear thinking about.

Jarrett,
I think it’s too early to criticize the technical aspects of this vehicle: it is a prototype after all, and the details will be fixed later. What is interesting in my view is that they conceived an elevated public transport system, without any elevated infrastructure which is brilliant, as long as you agree that a city may need an elevated public transport system, which is not granted.
The new cities in China badly need mobility, and the Chinese are well aware of the advantages of public transport. On the other hand, there is an emerging, aggressive and growing middle class, and a prosperous ruling class, who will not by any means give up their cars. And I can bet that the decision makers behind this straddle bus are part of this class, therefore taking somewhat interested decisions.

This bus, or train or metropolitain, whatever we want to call it, is huge, spacious and moves out of congestion. Its visual impact is far lower than a double-decker highway, even accounting for the monorail-style stations. And finally, I welcome any concept that brings new ideas to public transport. Public transport has a huge image problem and it badly needs new ideas, be they BRT, automation or even this. After all, even Curitiba’s BRT was criticized for its impacting elevated stops.

The straddle bus may prove to be a failure, but in this case, it will be easier to get rid of it than to demolish a monorail track or an elevated BRT infrastructure.

I disagree that demonstrations like this are good for transit in general. To me, they reinforce the idea that transit is secondary (at best) to private automobile traffic, and at worst provide an excuse for transit “skeptics” to oppose traditional/proven methods to move people in mass quantities.

To pick one example, the government of the state of Maryland recently canceled a major subway project in Baltimore (the Red Line) yet is moving forward with an expensive study of maglev between DC and Baltimore in large part because the governor visited Japan and became enamored with the technology.

Despite the fact that this “straddle” system is not practical in Europe/North America for the reasons Jarrett outlined, the reaction has already been “wow, this is cool!” in the tech sphere, and I strongly suspect it will be trotted out as part of anti-transit arguments, much like hyperloop, maglev, etc., not to mention the utopian forecasts of self-driving vehicles.

Which means you have these heavy, load bearing, structural members that have to be accelerated and decelerated every stop.

It also means that infrastructure is attached to a vehicle with a 10-20-40 year lifespan, instead of a 70 year lifespan.

If people are so concerned with visual impact of elevated structures, then reduce the visual impact. If there are concerns with shadowing, then explore fine-grained lattice structures. Heck, there’s plenty of places (like here in Texas) where a bit of shade is an advantage.

1) Will it only be moving in the direction of the traffic flowing below it (with another one of these beasts moving in the opposite carriageway), or might we see this thing moving AGAINST the cars underneath?

2) Given the high ratio of seats to door space (compared to standard-gauge rail), I imagine that dwell times will be problematic for rapid transit applications. This thing might work better for commuter applications (long distances between stations), where stopping for several minutes to load/unload is less of a problem.

The width of the tracks taking up the equivalent to one full lane says it all to me – especially considering, as stated by another commenter, it will take longer to enter/exit than a train due to limited doors.

Also I am interested to know how cars will exit the freeways it runs on without incidents, especially considering the human factor (because, yes, blanket all cars are flawless automatic & networked/talking together is still a ways away)

So let us ask about tare weight per rider. Seems to me that the straddle bus will cost more kwh to move each passenger than electrically powered railcars (even without regen braking). The beauty of an elevated is the static nature of the track structure which mostly sits there merely requiring periodic maintenance while the actual train cars which have a finite service life are the easily replaced items. Applaud the imagination, but this is not the prize winner.

Is there any good reason why it runs on rubber tires? It already needs rails for guidance and presumably electrical pickup. Like other people have pointed out it has to carry around a lot of structure, so it’s going to be heavy. It will need a concrete trackway to support the weight anyway.

The point about loading times is a good one too, it seems to be more than double the size of a suburban rail car, but still has only two relatively narrow doors per side. The stop times are going to be measured in minutes.

It really feels like the old saying ‘if that’s the answer to your question you’re asking the wrong question’ applies here. About the only thing it has going for it is capacity, but even that is offset by the less than optimum passenger compartment shape.

There appears to be plenty of space on the vehicle, so perhaps if the seats were set more to the inside and a space margin was placed near the walls, that would create space for very large slider doors. As for dwells, you could perhaps adopt a spanish metro solution where one side is for boarding, and another side is for exit.

I just don’t get it? Why not just build an elevated railway? You can easily fit double-track standard gauge rail in the width of a road – so you can go both directions in the same space. And you can use off-the-shelf hardware; haven’t we learn how important off-the-shelf hardware is for any system?

On Shangaiist there’s a video and at about 2:20 it shows a car crash/traffic jam – what does the straddle bus do when something’s in the way? It pumps the emergency breaks and out come the evacuation slides.

If something is blocking it – it can’t go. At least an ordinary bus can re-route or something. For the level of ambition, size, volume, cost of this idea – this thing running in mixed-traffic in streetcar-like conditions ought to be a non-starter. I’m gonna take a wild guess and assume the drivers in Shanghai are not the world’s best either.

If you watch the video with the animation of this thing working, then entire bus bends like a snake… Not at articulation points, but the whole side of the thing curves… Obviously this isn’t how the real life version is supposed to work, but if they can’t make an animation of this thing turn, how the heck do they propose a real one will… Corners will be massive.

As the limitations of this technology are found (and there are many) perhaps new ideas better suited for moving large numbers of people quickly and efficiently in mixed-traffic urban areas will evolve. Or people will decide that anything the straddler can do regular buses can do better with similar infusions of cash. Pretty expensive conversation starter, though.

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Since 1991 I've been a consulting transit planner, helping to design transit networks and policies for a huge range of communities. My goal here is to start conversations about how transit works, and how we can use it to create better cities and towns. Read more.